basement fires

Basement fires…some thoughts.

Sub-Grade fires, basement fires, or whatever you wish to call them will be some of the more difficult fire problems you will ever encounter in the fire service. These events take place in confined areas, 'access challenged' areas, and very often offer poor opportunities for direct ventilation.
Ventilation options may be limited to breaching outside doors and windows. Attack crews may benefit from the use of power fans as a ventilation tool. Due to the pressure that a power fan generates inside of a space, consideration should be given to fan placement and the effects of fan discharge. Gas or electric powered fans placed into first floor access point may provide sufficient pressure to force gases out of basement doors and windows. Water powered fans that introduce water vapor into these spaces may also be of some benefit in reducing heat while pressurizing the involved basement.
The channeling of smoke and heat away from the entry points into the basement should reduce the exposure for crews making entry into the sub-grade area.
Placement of fan(s) on the outside of the building in a manner that places the fire between the draft opening and the uninvolved portions of the structure may force fire and combustion products into these areas of the structure. That said, it is also important to say that the Fire Officer electing to utilize mechanical pressure to increase the tenability of the workspace might find precious few alternatives. Ventilation procedures for sub-grade events should be incorporated into pre-incident action plans and practiced whenever practical.

Access is a 'catch 22' situation where the firefighter must enter a super-heated chimney to get into a position to put the fire out. Access into these spaces also infers that a retreat will also encounter super heated flue like conditions on the way up and out. It is critical that crews operating into basement areas are provided back up from properly equipped hose teams. Due to the fire loading and design, these areas are often huge generators of BTU's and therefore require big water. These types of fires are good venues for class-A foam attack.
Basements are often the repositories and staging areas for all manners of materials. Narrow aisles, stacks of boxes, machinery spaces, elevator pits and sumps, and heating appliances are some of the obstacles and hazards found within these areas. The extent to which a space is used for the storage of combustible materials has a direct impact on the amount of suppressive water that must be used to extinguish a fire. Class-A foam will be well applied here due to its properties of heat absorption and penetration into combustible materials. You want these fires to go out fast and for good.
Rescues may be made more difficult due to these same access issues. Sub-grade search and rescue operations will require a superbly coordinated effort between search crews and suppression teams. Speed is essential. Exposed structural members place the stability of the entire structure at risk. Below grade fires often occur in unfinished areas of a structure that expose combustible components to direct heat and flame contact. If the components incorporate lightweight construction and light steel connectors the threat of rapid and catastrophic structural failure should be a primary consideration. It is an 'absolute' condition of pre-emergency preparation that crews are familiar with the structures within their response areas. Every crew, every Fire Officer should know where the commercial basements are and should have an understanding of the typical residential construction within their first or second due districts.

Visual clues for first arriving crews include:

Smoke issuing from a chimney on a hot day. It is not unusual to have a furnace or fireplace in the basement of a structure. It would be unusual to see smoke issuing from it on a hot summer day.
Smoke that exits from all floors of a multi story structure or smoke that completely fills the openings of a single story building. The smoke level within a structure gives the fire officer important clues as to the level of the fire.
Higher smoke levels within a structure, or opening, indicate a higher source of fire.

Tactics for basement fires usually provide for the protection of interior points of access. Entry into a basement or sub-grade area from an interior stairwell should be accomplished quickly to reduce the time firefighters spend in the heated up-drafts. It will be considerably hotter in the stairwell than on the basement floor. Basement and sub-grade fires are ideal candidates for class-A foams where knockdown and suppression must be done quickly to reduce physical risk and preserve the structure for rescue. Remember that unprotected structural members equate to early collapse and older structures often offer ample opportunity for rapid-fire spread due to the presence of void spaces and 'poke holes'. Speed, therefore, is essential.

The use of distributor nozzles and piercing nozzles should be considered as one means to temporarily deliver water into these spaces, at least until you can go down the steps with a hand line and finish the job.